Dry adhesives are sticky and are used to bond objects together. Typically, dry adhesives may only be applied under dry conditions (i.e. non-aqueous conditions), or are otherwise non-reversible.
Mussels are known to adhere to a wide variety of surfaces under both dry and wet conditions. It is believed a protein containing a high content of catechol (catecholic amino acid 3,4-dihydrocy-L-phenylalanine (DOPA)) may be responsible for the mussel's ability to adhere in both wet and dry conditions in which most adhesives function poorly. Lee, H., et al., Nature 448, pp. 338-342 (2007); Lee, H., et al., PNAS Vol. 103, No. 35, pp. 12999-13003 (Aug. 29, 2006). Both natural and synthetic adhesives containing DOPA and its derivatives have demonstrated strong interfacial adhesion strength. Studies have indicated that DOPA may form strong yet reversible bonds with surfaces, especially oxide surfaces.